After humans, now birds are affected by noise pollution. The new study has revealed that noise pollution develops some physiological signs related to chronic stress in birds. It also affected the growth rate in chicks. The study was conducted by the researchers from California Polytechnic State University and the Florida Museum of Natural history. It was funded by National Geographic and was published on 8th January in the journal Proceedings of the National Academy of Science (PNAS). The team researched the western bluebirds, which nesting sites are surrounded by natural gas treatment facilities in northern New Mexico. They fund that they hatched fewer eggs than the blue birds living in quiet places.
When the team examined blood samples of 240 blue birds from that noisy area, they detected physiological symptoms which are similar to post-traumatic stress disorder in humans.
Nathan Kleist, lead author and who conducted the research while at CU Boulder and graduated with a Ph.D. in evolutionary biology, said that high noise level could dramatically impact the blue bird’s stress hormones and also fitness. Before that, it was assumed that the birds are most tolerant to noise, but now they have more negative effects, he added further. Noise pollution from human activity has now become more dangerous for wildlife.
This is the first such study which has shown the effect of noise pollution on wild animals. Now it is high time to think about it, the team said. During the study, the team examined three species of cavity-nesting birds. It included western and mountain bluebirds and ash-throated flycatchers. Then the team erected 240 nest boxes on 12 pairs. They tested their blood samples for three breeding seasons. They also analyzed the hatching success rates, nestling body size, and feather length. The high noise level had lower the levels of a key stress hormone called corticosterone.
Co-author Christopher Lowry, a stress physiologist in the department of integrative physiology at CU Boulder, informed that with inescapable stressors, including post-traumatic stress disorder (PTSD) in humans, stress hormones are often chronically low.
On the other side, the chicks also suffered from the high noise level in that area. They detected low rate in feather growth and body size.
Senior author Clinton Francis, an assistant professor of biological sciences at Cal Poly said that any kind of dysregulation could act negatively for some species, even though the stress hormone levels are high or low. As the noise effected reproductivity, the team was able to detect that dysregulation.
Some previous study has been shown that some species like to leave noisy areas, but this study informs about the effect of staying in such areas. This is also called as an ecological trap.
One of the most powerful bird-protection law has been passed in 2018 known as the Migratory Bird Treaty Act. Many nature lovers have come together to protects birds. After this study, the humans should work together to reduce noise pollution and to save the blue birds.